lördag 13 juni 2015

The Creation of Quantum Mechanics: The True Story by J Hendry Part 1

a genuine "history" as opposed to a mere technical report or popular or semi-popular account.

My aims in making this attempt have been to satisfy the needs of historians of science and, more especially, to promote a serious interest in the history of science among physicists and physics students.

Hendry states in the Introduction:

On one hand the quantum theory has continued in all its formulations to show a remarkable predictive power in respect of experimental observations. In this respect it must rank as an extraordinarily successful physical theory, and as one that will not easily be displaced.

On the other hand, however, dissatisfaction with the conceptual foundations of the theory has also apparently endured.

Many working physicists are seemingly content to accept what Einstein referred to as the "gentle pillow" of the Copenhagen interpretation without asking any further questions, and this has long been accepted as an orthodox position.

But if we restrict our attention to physicists (or indeed philosophers) of the first rank, then we see immediately that such an orthodoxy is illusory. It was created in the late 1920s when many of the leading quantum physicists, among them Bohr, Born, Heisenberg, Pauli, Dirac, Jordan and von Neumann, sunk their more philosophical differences in an effort to repel the challenge of the semi-classical interpretations and get on with the job of developing quantum electrodynamics.

But those differences remained. Copenhagenism was and is a generic term covering a whole range of related interpretations. Even when these interpretations are taken together, they cannot be considered as an entirely dominant orthodoxy. Among their early opponents some physicists might arguably be dismissed as narrow-sighted conservatives. But such outright dismissal is very difficult to uphold in Einstein's case, and still more so in those of Schrödinger and de Broglie, neither of whose preferred interpretations could reasonably be labelled classical.

More recently attention has shifted from the physical interpretation of quantum mechanics towards the logical and mathematical consistency of quantum field theory, but the issues remain closely connected and opposition to Copenhagenism remains strong.

However, and here lies the crux of the matter, the opponents seem to be no nearer to providing a valid alternative than were their predecessors of the late 1920s.

Beyond the limited compromise of Copenhagenism there is still no such thing as a consistent and generally acceptable interpretation of quantum mechanics, and the evidence of the last fifty years points unerringly to the conclusion that there will not be one until either the structure of our physical conceptions, or our expectations of physical theory, or the quantum theory itself should undergo radical changes more far-reaching than any yet seen.

Faced with this dilemma it is tempting to react as did Peter Debye to the problem of electrons in the nucleus, a problem that arose in the immediate wake of quantum mechanics, by treating it as something best ignored, "like the new taxes".

And many physicists have indeed taken this course, either ignoring the interpretative problem altogether (paying the taxes without question) or proceeding stubbornly to seek fundamentally classical interpretations that are demonstrably not there (stalling the taxman).

But whereas such attitudes may be expedient in the short term they are ultimately inconsistent with the very spirit of the scientific enterprise.

The interpretative problem of quantum theory is several orders more fundamental than that of nuclear electrons, and has proved immensely more resistant to attempts at a solution.

But a theory with innate inconsistencies, whatever its present predictive success, cannot be expected to serve for ever.

If the problem, like the tax, does not bear thinking about, then that is the strongest indication we can possibly have that it needs thinking about.

And while it may not be so easily solved we can at least try to understand how such an extreme situation arose in the first place.

One aim of this study, then, is to approach the history of the theory of quantum mechanics as a means of exploring its philosophy.

What Hendry effectively says is that the foundations of quantum mechanics as physical theory was an inconsistent mess at start hundred years ago and has so remained until now. How is it then possible that this inconsistent mess "has continued in all its formulations to show a remarkable predictive power in respect of experimental observations"?

Well, the answer is that since quantum mechanics as a multi-dimensional inconsistent mess is uncomputable, it is impossible to make predictions from theory alone. This means that whatever observation is made, there is a version of quantum mechanical messy theory that can be made to conform with the observation. This is the reason why there is no observation in conflict with any quantum mechanical theory, even though the theory is inconsistent, which of course is used as evidence that the inconsistent messy theory is perfect and consistent and always in perfect consistent agreement with observation.

In Part 2 I will summarize Hendry's account of the genuine "history" and then ponder Hendry's appeal:quantum theory itself should undergo radical changes more far-reaching than any yet seen.